Two childhood friends locked in battle for the top spot in the finale of the year-end championships.
After his 24th consecutive victory, 6-3 6-4 in London on Sunday, Murray -- who was the No. 1 heading into the clash -- is that man. He joined coach Ivan Lendl, boyhood idol Andre Agassi and Djokovic in an exclusive pantheon of just 17 players to have held the year-end No. 1 since the ranking system began in 1973.
"To finish the year world No. 1 is very special. It's something I never expected," Murray, the home favorite from Scotland who lives near London, reflected after the match.
"I couldn't have done it without my team. My family as well -- they've been around for a long time and made a lot of sacrifices for me."
It was a feat of endurance the Brit had made it here at all. Two record-breaking matches
had led to speculation the 29-year-old wouldn't be able to go the distance against an apparently reinvigorated Djokovic. On Saturday in the semifinals, when Murray saved a match point, he needed three hours, 40 minutes to see off Milos Raonic.
But buoyed by a sell-out home crowd of more than 17,000, he quickly dispelled any lingering doubts to take the match on his third Championship point when a misfiring Djokovic committed his 30th unforced error. The four-time defending champion was finally beaten.
The last time Djokovic, Roger Federer or Rafael Nadal -- Murray's fellow "Big Four" members -- didn't finish as the year-end No. 1 was in 2003.
"Today we were both part of history," a gallant Djokovic told the crowd. "It was an honor to be on the court and part of the big occasion.
"Andy's definitely No. 1 in the world. He's the best player and definitely deserved to win."
Their last meeting -- June's Roland Garros final -- saw Djokovic become the first man to hold all four majors simultaneously since Rod Laver in 1969.
But 2016 has been a year of two halves and this wasn't the Djokovic of Roland Garros.
Both hit the same number of winners at the O2 Arena -- 13 -- but the Serb committed twice as many unforced errors as Murray. Pinned back behind the baseline playing uncharacteristically reactive tennis, his rock-solid backhand particularly let him down.
"Every time I got an opportunity, I would miss," lamented Djokovic, who relinquished the No. 1 ranking two weeks ago. "Just too many errors. For me it wasn't a great match in terms of play.
"Again, because of the player he is -- and because you know you're always going to get the ball back -- I guess that's what makes you think about the risk management.
"Today certain things just didn't work out as well for me."
Murray admitted there had been unusual mistakes from both players but rightfully stressed "you never beat a player as good as Novak if you don't play well."
And, having confirmed his status as the year's best men's tennis player in the final match of the season, he expressed his intention to remain at the top.
"It's taken a huge effort over the last five, six months to get to No. 1 -- I would obviously like to stay there.
"I'm aware that's going to be extremely difficult because I had a great year and only managed to do it by one match.
"But now that I've got there, I'll obviously be motivated to stay in that position."
Murray started the affair in shaky fashion, hitting a double fault on the first point and then another later in the game. Djokovic's inability to capitalize would prove telling.
And after not losing a point in his first two service games, Djokovic's struggles on serve began.
He had to fend off two break points in a curious sixth game. Exemplifying his erratic play, Djokovic miscued on a simple looking smash at the net, dumped a swinging volley into the net with Murray in trouble and let a Murray backhand go, thinking the shot would go wide -- when it didn't.
Murray broke through in the eighth game for 5-3 and padded his advantage early in the second.
Cutting Murray's lead from 4-1 to 4-3, Djokovic took the opening point on his pal's serve, only to then send a routine forehand into the net.
Back in early June, not many would have predicted this type of outing from Djokovic.
A smart Murray, meanwhile, played solid, steady tennis -- and got his reward.
"This is the best possible way obviously to finish a year," said Murray.